Hydraulic remote control system



March 27, 1945. l

L. E. DOUGHERTY HYDRAULIC REMOTE CONTROL SYSTEM I Filed April 29. 1943 VINVENTOR. LEMUEL E. Baud/15am HTTORNEY March 27, 1945. L.- E. DOUGHERTY 2,372,189

, HYDRAULIC REMOTE CONTROL SYSTEM Filed April 29, 1943 2 sheets -sheet 2 INVENTOR. LEMUEL E. oouafienrr WflW HTTORNEY pasta Mar. 21, 1945 UNITED STATES PATENT OFFICE, HYDRAULIC REJSE ZZNTROL SYS'ITEM v Application April 29, 1943, Serial No. 484,99

4 Claims.

This invention may be considered a further development of my hydraulic remote control system as described in my co-pending patent application, Serial No. 484,998, filed April 29, 1943. In

said application, means are provided whereby expansion or contraction or the hydraulic fluid in the connecting tube between the transmitter'and receiver is automatically compensated for so that the transmitter and receiver remain in synchronization regardless of temperature changes and consequent expansion or contraction of the 111- draulic fluid in the system; Thi compensating meanswas adapted to a control system of the single tube type in which resilient loading means are applied to the transmitter piston and to the receiver piston so that the fluid in the cylinders and the connecting transmission tube or duct is held under compression.

While a control system of this type may work satisfactorily in many installations, the transmitter and receiver assemblages must necessarily be of considerable bulk and weight inasmuch as vide an arrangement such as specified above wherein a single fluid compressor is employed for supplying fluid pressure to the transmitter and receiver, means for normally connecting the transmission line and the return line between the transmitter and receiver to the compressor; butupon actuation of the transmitter both lines are disconnected-from the compressor, thus making the system a closedsystem. This permits actuation of greater loads with the same size pistons Fig. 2 is a diagram of a single compressor'unit used in conjunction with a plurality of operating heavy springs must be provided tor the proper return action in the system.v In systems of this type there is also the problem of obtaining springs which will apply substantially constant fluid pressure in the system in all positions of transmitter and receiver. In many installations, such as in will apply a predetermined fluid pressure at all times to the transmitter and the receiver.

It is a further object of this invention to provide for fluid pressure for an arrangement in which a plurality of fluid transmission systems are employed, each'system comprising a transmitter, a receiver and a connecting duct, in which a single source of fluid under pressure is employed to provide the fluid pressure for all of said transmitters and receivers.

Still another object of this invention is to provide a singlev source of fluid under pressure in a plurality of fluid transmission systems in which a common pipe leading to all or said transmitters,

and a common return pipe leading from all of said receivers may be employed.

Still another object or this invention is to pi ro Fig. 3 is a cross sectional assembly view f a modified form of hydraulic control equipmentin which dual lines are employed between each transmitter unit and receiver unit and also employs a modified form of locking apparatus in the receiver.

Referring to Fig.-l, the transmitter unit A is connected by the tube or transmission duct 42 to the receiver unit B from whence the connectin or return tube 38 returns back to the transmitter unit and by the tube 36 to the compressor unit C. While the compressor unit C here illustrated is of the type which will maintain a substantially constant fluid pressure in the system, such a type of compressor'need not necessarily be used. As the parts of the system are inter-connected and always in balance, the proper operation of this system does not depend upon constant fluid pressure. The fluid pressure maintained by the compressor unit must be suflicient for movement of the receiver piston in one direction and as a holding means against unauthorized movement.

In the operation of this device a suitable lever 01' other control device may be connected at III to the transmitter piston rod M in order to transmit movement to the piston 5| and rod 56 of the receiver, the load being connected to rod 56 at 49. The fluid pressure from the compressor through the line 3.6 and the fitting 31 is present in the upper part. of the transmitter cylinder- 45, thus exerting downwardforce on this piston so thatfluid in the lower part of the cylinder will be under the same pressure. v'I'he transmitter 'sor is disconnected.

' opens the passage ll,

- aforementioned the 1 compressor piston H is integral with or securely attached to the piston rod M. The receiver cylinder and pieton are very similar to the transmitter cylinder and piston, fluid pressure from the compressor being present in the upper part of the receiver cylinder 50 by means of the return tube 38. This tube 38 is at all times in open communication with the upper ends of cylinders to and 50 and with .the compressor C. Thus it will be seen that a predetermined fluid pressure from the single source, 1. e., compressor C, supplies the pressure for both the transmitter and the receiver.

The transmitter is equipped with the same type of valve apparatus as described in Fig. 4 of my said co-pending-application, Ser. No. 484,998, that is, the piston type valve 23 normally closes the passage i1 between the transmitter cylinder and the connecting tube 2 to the receiver and opens the passage 21 which, by means of the passages 2e and 25, provides fluid connection between the compressor unit and the receiver. Fluid pressure from the compressor unit by means of the tube 36 and passages 25 and 26 is present in the chamber 2t and acts upon the upper end of the piston valve 23. Fluid pressure from the lower part of the-transmitter cylinder by means of passages ii and i8 is present in the-chamber i9 and acts against the lower endof the piston valve.

With the system at rest these fiuid pressures at both ends of thepiston valve are equal, so it remains in the position shown with the transmitter disconnected from transmission duct 62 which is in communication with the compressor. Force exerted downwardly on the transmitter piston, increasing the fluid pressure in the lower part of the cylinder, causes upward movement of the piston valve; overcoming the force of the spring 30, thus closing passage 21 and opening passage I? so that the transmitter cylinder is then connected to the receiver and the compres- Upward movement of the transmitter piston and consequent lowering of pressure in the lower end of the cylinder allows downward movement of the piston valve dueto the fluid pressure .from the compressor being greater than that at the lower end of the valve. This, of course, also.closes the passage 2! and so that fluid may flow from thereceiverto the transmitter and the compressor is disconnected from the system. It is thus seen that with the system at rest that the connecting. tube 42 is disconnected from the transmitter but isopen' to the compressor unit so that expansions or contractions of the fluid therein will cause no movement in the transmitter.

in the receiver assemblage a locking valve is employed very similar to the locking valve as used in my said co-pendlng application, Ser. No. 484,998, and claimed in my co-pending application, Serial No. 449,942, flled July 6, 1942. However, as this is a common fluid pressure, this locking valve apparatus is adapted to use this common source of iiuid pressure, rather than heavy springs tendmg to balance such pressure as described in application. Fluid pressure from unit is present in the tube 88 and conveyed by the tube 10 into the chambers II and 16. Fluid pressure fromthe transmitter, by means of the tube 42, the passage 65 and connecting passages, is present in the chambers 63 and 64 at the opposite sides of the diaphragm:

14 and 18. The tube 42 is normally connectedbalanced system subject to a asvaise to the compressor unit through the valve 22; ii the transmitter so that the fluid pressure upoi the opposite sides of these diaphragms are equal The compression spring 13 seated upon the dia phragm l4 normally holds the valve 6i closed The compression spring 19 seated upon diaphragmJl'no'rmally holds the valve to closed With both valves closed, there is no eonnectiox to the receiver cylinderr This, of course, efiectively locks the receiver, asany tendency of the piston to move upward encounters the fluid pressure from the compressor unit, and any downward movement of the piston is prevented by allowing no escape for the fluid in the lower part of the'cylinder. An increase in fluid pressure from the transmitter, caused by the operator's exertion oi force to move the piston downwardly, causes the valve 61 to open. Movement of the trtter piston in the opposite direction and consequent decrease in fluid pressure from the transmitter will cause the valve to to open. Ii either valve 6'! or valve 68 is open, fluid connection between the receiver cylinder and the transmitter cylinder is obtained. These valves are normally closed and lock the system but unlocls and allow passage of fluid between transmitter and receiver upon authorized movement of the transmitter piston.

Any expansion or contraction or the fluid in either of the connecting tubes between the transmltter and receiver will cause movement in the compressor unit but will cause no movement in either the transmitter or receiver. The pistons of the receiver and transmitter, when once established in proper relation, will remain in synchronization regardless of temperature changes to which the connecting tubes may be subject.

' To establish the proper relation of the transmitter piston to the receiver piston and resynchronize the transmitter with the receiver, as it becomes necessary, I employ a shut-off valve 68 and the connecting tube 39 between the upper and lower ends of the transmitter cylinder. It is apparent that with the valve t8 open movement of the transmittr piston will bypass fluid from one end of the transmitter cylinder to the other without causing any movement in other tube ll.

parts of the system. By moving the receiver piston to one end of its stroke and then opening the valve 48, the transmitter piston can then be moved to its proper position at the end or its stroke. Valve 48 is thenclosed and the pistons are established in proper relation to each other. It should be observed that while the upper ends of both transmitter and receive cylinders are always open to the compressor, no actual movement in the compressor takes place through the operation of this control system. Therefore the volume of the compressor need only be sumcient ,to compensate for expansions or contractions-oi the fluid in the connecting tubes. K

In Fig. 2 is diagrammatically illustrated a plurality 01' independent controls connected to a 3111-. gle"compressor unit. Th transmitters 96a, e541. 86a, 91a are connected to corresponding receivers 84b, 95b, 98b, 911) by the tubes 98, 99, I00 and I 0| respectively. All of the transmitters may be. connected to the common tube 92 and all the receivers to the common tube eawhich are then connected to the compressor all by the A system or this type ofiers great saving in weight and size of the individual units over a system in which springs must be provided at each individual transmitter and receiver unit,

and also provides a great saving in weight over the conventional dual line systems.

Referring to Fig. 3, there is illustrated a modincation of the apparatus as illustrated in Fig. 1 in that it provides, in addition,'for making a closed system during operation. one advantage of this is that by using the same. piston areas and normal fluid pressure twice the force can be transmitted than with the type of system shown in Fig. l, which is always open to the compressor unit. This system will operate under a much heavier load upon the receiver with the same pressure from the compressor unit than would be possible with the previously described system, as fluid pressure generated in the compressor is used only to lock the system and not to move any load.

The transmitter assemblage is very similar to II6. As soon as this valve has moved and dis-.

- connected the compressor from the system there that already described in Fig. 1- and parts of which are identical with those in Fig. 1 have the same designating numeral primed. The only difference in this transmitter assemblage and that shown in Fig. 1 is in the valve assemblage in which a different arrangement of the passages provides for disconnecting the fluid connection fromthe upper part of'the-receiver cylinder from the compressor unit whenever motion is imparted to the transmitter. There is no direct connection from the compressor to the transmitter cylinder, through thesliding piston valve 6. Fluid pressure from the compressor through the tube III! and the passage II5 is present at the upper end of the piston valve, and,. with this valve in its normal position, may pass through the passages Ill, III and H0 and the tube 34. By means 0! the T-fltting I22 the fluid under pressure enters the transmitter cylinder, and by means of the tube I23 enters the receiver cylinder. Fluid connection from the connecting tube I to the compressor unit is by means of the passages H3, H2, Ill and H4, thence by the tube 8 tothe com pressor unit. An increase or decrease in fluid. pressure in the lower part of the transmitter cylinder causes movement of the piston valve I 6 and closes both the passages H2 and III, thus disconnecting the compressor from both sides of the compressor is present at both ends of the piston valve I58 in the chambers I54 and I62.

The pressure or the compressor is applied to chamber I62 by way of passages II8, II, III, H2, H3, I20, I59, and I63. Springs I53 and I65 in said chambers normally centralize the valve. Movement of the transmitter piston downwardly, thus increasing the fluid pressure in the lower part of the transmitter cylinder and disconnecting the compressor from the system causes an increase in fluid pressure in the chamber I62, thus shifting the piston valve until its port coincides with the passage I59, thus allowing the passage of fluid to the lower part of the receiver cylinder and consequent upward movesuch connection being made is an increased pressure in the upper part of the transmitter cylinder and a decreased pressure in the lower part of the transmitter cylinder. As the two ends of the sliding locking valve I58 are now subject to the pressures in the transmitter cylinder, the valve will move downwardly, thus opening the passage I59 and allowing fluid to flow from the lower part or the receiver-cylinder to the transmitter cylinder. This is then, in effeet, a dual line pulsator system; but upon the cessation of movement or the transmitter piston,

both sides are reconnected to the compressorand the receiver piston is hydraulically locked against downward movement by the piston valve I58. At the'same time, piston II is also locked against downward movement so that temperature variations in the fluid will not destroy synchronism between transmitter and receiver but will only aflect the compressor.

Use of the sliding type of locking valve, rather than the poppettype valves and diaphragms, has

cylinder. The piston I30 is supported slidably ly high or extremely lowfluid pressureshould upon an enlarged section I3tof the piston rod I29 and is equipped with the packing I3I to prevent leakage. The spring I36 is preloaded between the spring retainers I31 and I35. The spring retainer I35 seats against the shoulder of the piston rod caused by the enlarged part I34 thereof, while spring retainer I31 abuts against lock-nut I88 on rod I28. Likewise, the force of the spring I39 is normally against the shoulder on the piston rod. Both th springs I36 and I35 are preloaded so. as to prevent any movement of the piston under normal operating loads, but will allow movement of the piston if an extremedevelop in one end oi the cylinder. If the re ceiver piston is at the upward extent of its stroke and thermal expansion of the fluid in the cylinder below the piston should take place, the p ton could move upwardly against the force of the spring I36 sufliciently to prevent a destructive pressure from arising. If the receiver piston is at the lower extent of its stroke and subsequent thermal contraction of the fluid take place/so that pressure below the piston decreases until me'nt of the receiver piston. Upward movement oi the transmitter piston causes a reduction of it approaches atmospheric pressure, then the receiver piston will move downwardly against the force of the spring I35 and prevent the fluid pressure from falling below atmospheric pres sure and subsequent danger of air entering the it understood that the apparatus shown is only illustrative and that the invention can be carried out by other equivalent means. Also, while it is designed to use the various features and ele- 1 ments in the combination and relations described, some of-these may be altered and others omitted without interierin} with the more generai results outlined, and the invention extends under predetermined pressure, means for nor-' mally disconnecting said duct from said transmitter and said receiver and connecting said duct to said chamber, and means responsive to the actuation of said transmitter and effective as long as said transmitter is being actuated for disconnesting said duct from said chamber and connecting said duct to said transmitter and said receiver.

2. In a fluid transmission system comprising-a transmitter, a receiver and a duct adapted to connect the transmitter and the receiver, a cornpressio'n chamber having a supply of fluid and means for placing said fluid under predetermined pressure, means for causing said fluid to main= tain said transmitter and said receiver continuously under predetermined pressure, means for normally disconnecting said duct from said transmitter and said receiver and connecting said duct to said chamber, and means responsive to the actuation of said transmitter for discon asraiiss meeting said duct from said chamber and corinecting said duct to said transmitter and said receiver.

3. In a fluid transmission system, a transmitter, a. receiver, a transmission duct connecting said transmitter and said receiver, a return duct connecting said transmitter and said receiver, a compression chamber having a supply of fluid and means for placing said fluid under predetermined pressure, a connection from said chamber to said return duct, means for normally disconnecting said transmission duct from said transmitter and said receiver and connecting said transmission duct to said chamber, and means responsive to the actuation of said transmitter for disconnecting said transmission duct from said chamber and connecting said transmission duct to said transmitter and said receiver. v

4. In a fluid transmission system, a transmitter, a receiver, a transmission duct connecting said transmitter and said receiver, a return duct connecting said transmitter and said receiver, a

compression chamber having a supply of fluid and means for placing said fluid under predetermined pressure, means for normally connecting said return duct to said chamber, means for normally disconnecting said transmission duct from said transmitterand said receiver and connecting said transmission duct to said chamber, and means responsive to the actuation of said transmitter for disconnecting said transmission duct and said return duct from said chamber and connecting said transmission duct to said transmitter and said receiver.

LEMUEL E. DOUGHERTY. 

